Spark-plug.



PATENTED APR. 17, 1906.

B. W. HALLSTEAD.

SPARK PLUG. APPLICATION FILED NOV.5, 1904.

UNITED STATES PATENT orrr on.

BERT W. HALLSTEAD, or soRANToN, PENNSYLVANIA.

8 PA R K- P L U G Specification of Letters Patent.

Patented April 17, 1906.

Application filed November 5, 1904. Serial No. 231,580.

To all whom it may concern:

Be it known that I, BERT W. HALLsTEAD. a citizen of the United States, residing at Scranton, in the county of Lackawanna and State of Pennsylvania, have invented certain new and useful Improvements in Spark- Plugs; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in sparking apparatus for explosive engines,

and more particularly to a sparkin plug provided with means for preventing Toss of current by short-circuiting or by the jumping of spaces at points other than Within the explos1ve-eng1ne.

With this and further objects in view the invention comprises certain novel constructions, combinations, and arrangements of parts, as will be hereinafter fully described and claimed.

In the accompanyingdrawings, Figure 1 represents a view in side elevation of a sparkplug embodying the features of the present invention. Fi 2 represents a longitudinal vertical central section taken therethrough.

In the igniting of explosive charges within the cylinders of as-en ines it has been a difficult matter to e ectua ly control the currents of electricity supplied for producing 1 sparks, such currents being necessarily of high potential and readily leaking or straying wherever insufiicient insulation occurs or jumpin any short spaces, and in order 'to avoid t s waste of current and insure the sparkin bein produced within the cylinder of t e exp osive-engine, as well as to attain'other valuable results, I employ a structure such as is disclosed in the accompanying drawings, iii which v 1 represents the casing or body portion of the plu which is formed with a reduced threade shank 2, the enlarged portion of the plw being provided with a polysided outer surface 3, adapted to be engaged by a wrench for threading the shank 2 into the aperture provided therefor in the cylinder of the en gine. The shank 2 of the plug is bored lon itudinally, and a conductor4 extends centrafiy throughout the length thereof, as well as through the enlarged body portion, and at its inner or sparking end is preferably provided with a tip of platinum, as at 5. Of course the use of platinum is arbitrary; but in practice the same serves to prevent destruction of the conductor. The shank 2 is internally threaded at its inner end, as at 7, and a cap 8 is threaded into said shank, a ring 9 being arran ed within the shank 2 and a similar ring 10 eing arranged at the inner end of the threaded portion of the cap 8, the space between the rin s 9 and 10 being filled by mica or other suitaIfle insulating disks 1 1, through which the conductor or stem 4 extends, said conductor being supported by said disks and maintained at a suitable space from the shank 2. The cap 8 is made up of a hollow body portion which is threaded, as above mentioned, into the end of the shank 2 and a cover 12 carried at the outer end of said body portion. The cover 12 is apertured centrally, throu h which aperture projects the inner end of the stem 4, and said aperture is lined by a ring 13, preferably of platinum or other suitable material.

The stem or conductor 4 is threaded intermediate its length, as at 14, and engaging said threaded portion are sleeve-nuts 15 15, facing in opposite directions and having their sleeves either in contact or directed toward each other. ranged to engage mica or other suitable disks 16, surrounding the stem 4 and filling the space between the said nut and the annular shoulder 17, connectin the shank 2 with the main body portion of t e plug 1. The outer end of themain body portion of the plug 1 is internally threaded, and a caplS is threaded into the same and is apertured centrally, as at 19, through which aperture extends the stem 4, mica or other suitable insulating-disks 20 surrounding the stem 4 and being disposed between the outer nut 15 and the cap 18.

It will be observed that the nuts 15 serve to retain the stem 4 against longitudinal movement and that the mica disks 11, 16, and 20 retain the same against lateral movement and support the same spaced from the surrounding casing at all points.

The stem 4, while normally maintained, as above stated, against longitudinal and lateral movement, is capable of longitudinal adjustment by being threaded in either direction within the nuts 15, so that the tip 5 may be adjusted to a nicety with respect to the ring 13. The nuts 15 may be spread apart to any degree required for causing the opposite ends to engage the mica 16 and 20,

respectively, when the cap 18 is threaded home, so that such mica will be compressed upon for preventing leakage, and the danger of short-circuiting prevalent with ordinary insulators from defects in such insulators is lar ely obviated.

n' ractice the shank 2 is threaded throug the'wall of the cylinder of an engine until the inner end of said shank projects within the engine, so that the spark produced between the tip 5 and the ring 13. will readily ignite the charge within the engine, and the chamber formed in the cap 8 in the rear of the ring 13 permits of the ready circulation of gases between thetip 5 and the ring 13, suitable discharge-openings 21 21 bein formed in the wall of the cap 8 for permitting the discharge of gases entering the chamber within the cap 8. The circulation of the gases about the tip 5 and within the chamber formed within the cap 8 will tend to cool the said tip and the ring 13 and prevent excessive heating of the stem 1. In the operation; of a gas-engine when the charge of explosive gas has'been compressed within the cylinder the gases will -of course fill the chamber formed within the casing 8, and as soon as the compressing-stroke of the piston of the engine'is completed the circuit including the stem 4 andthe plug 1 will be closed by any ordinary make-and-break device, whereupon the resistance occasioned by the air gap between the tip 5 and the ring 13 will be overcome, due to the high voltage of the current, and a spark will be produced between said tip and ring which will ignite the ases surrounding said tip and explode the c arge within the cylinder.

Each of the nuts 15 is made of a material which expands under the action of heat more readily than does the material from which the cap 18 and the plug '1 is formed. The cap 8 is made of a similar material to the nuts 15,

so that during operation whenthe parts become heated the expansion of the material forming plug land cap 18 will not produce loosening ofthe insulating-disks 11 16, and 21; but as the cap 8 and nuts 15ex'pand at a C,glreater rate than the plu 1 and cap 18 the isks 11, 16, and 21 will be compressed and held firmly in place. While I do not limit my invention to any particular materials, for illustration I would suggest that the nuts 15 and the cap 8 might be made of brass, while the plug 1 and cap 18 might be made of steel and'the centrally therethrough,

. lating object above suggested attained. Of

course any other metals which are practical for the purpose might be used, so long as the relative ratio of expansion and contraction is maintained.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is V 1. A spark-plug comprising a body portion, a cap carried by said body portion, a conductor stern extending longitudinally through said of insulating material surrounding-said stem and engaginglthe walls of said body portion, for spacing t a similar body of insulating material surrounding the stern and engaging the cap for spacing the stem from the cap, and means carried by the stem and interposed between said bodies of insulating material for spreading said bodies apart and pressing the same against said body portion and cap respectively.

2. A spark-plug comprisin a body portion, a conductor-stem extending lon itudinally through the same, separate bodies of and engagingqthe walls of said body portion for spacing t e stem from the body portion, and a plurality of nuts interposed between said bodies of insulatin material and threaded onto said stem same in position.

3. A spark-plug comprising a hollow body portion, a stem extending throu h the same, insulating material engaging t said body portion and supporting cap and body portion, a body e stem from said body portion tor retaining the e walls of said stem insulating materlal surrounding said stem I out of contact therewith, part or said insu lating material beingirspaced from another part thereof, a nut t eaded onto saidstem between said parts of insulatin material and engaging one part thereof, and a second nut also threaded onto said stern between said parts of insulating material and engaging the other part thereof.

4. A sparklug comprising a portion, a stem extending longitudinally, disks of insulating material surrounding said stem and engaging the walls of said body portion for spacing the stem therefrom, and a pair of sleeve-nuts threaded onto saidstem between the disks of insulating material and engaging said disks for retaining dinal movement.

5. A spark-plug comprisin tion, a conductor-stem extending lon itudinally through the same, separate bo ies of insulating material surrounding said stem for spacing the same from the body portion, means spaced apart and carried by said stem and interposed between said bodies of insumaterial for maintaining the same in position, and means for retaining said interposed means against movement longitu dinally of said stem.

a body porhollow body v the stem against longitu sis s're 6. A spark-plug comprising a body portion of heat at a greater rate than the body tion, a conductor-stem extending through portion. 1 the same, insulating-disks arranged Within In testimony whereof I affix my signature said body portion and supporting said stems in presence of two Witnesses.

and nuts carried by said stem and engaging BERT W. HALLSTEAD. said insulating material for retaining the Witnesses: same in position, said nuts being formed of a W. W. BAYLOR,

material capable of expanding under the aov D. V7. WRIGHT. 

